Tim Weekley, age 11, of Stone Mountain,Georgia, for his question:

Where are the Eastern and Western Hemispheres divided?

The earth provides two definite markers that we can use to divide the Northern and Southern Hemispheres. They are the North and South Geographic Poles, alias the two ends of the axis around which the world rotates. We can figure the halfway point between them, which is the equator, and use it to slice the global map into equal north and south hemispheres. But we have no natural ground markers to help us to slice the global map into an Eastern and Western Hemisphere.

Geographers, however, have devised a neat network of latitude and longitude lines to section off the surface. These man made lines mark every spot with its north and south, east and west position. A map maker might want to slice equal Eastern and Western Hemispheres along the Prime Meridian that runs through Greenwich, England, and the International Date Line down the Pacific, half a world away. But the land masses are not arranged to suit this plan. What's more, people seem to have settled the matter in a way of their own. The populations of the Americas tend to regard their territory as the Western Hemisphere and to donate the biggest half of the globe to the Eastern Hemisphere.